Conventionally, various patches and patch preparations have been developed to protect the skin, administer a drug into the body through skin surface and the like.
Since synthetic rubbers used as an adhesive for an adhesive layer of a patch preparation do not have a functional group, they are preferable in view of the stability of a drug in the adhesive layer, and advantageously show good drug releaseability. However, due to the absence of a functional group, such synthetic rubbers are hydrophobic and, when an organic fluid component having high polarity is added to an adhesive layer, its low compatibility with the organic fluid component poses problems. That is, when the compatibility of the synthetic rubber and the organic fluid component having high polarity is low, the organic fluid component having high polarity blooms on the adhesive surface. As a result, the adhesive force decreases and the patch preparation adhered to an adhesion object is detached soon. Therefore, when an adhesive layer using a synthetic rubber as an adhesive is added with an organic fluid component in an attempt to impart a soft feeling to the adhesive layer, and reduce pain and irritation due to the skin adhesive force produced when detaching the patch preparation from the skin, only an organic fluid component having low polarity can be used as the organic fluid component, which also limits the drug to one with low polarity.
Examples of the documents aiming at resolution of the problem that occurs when adding a component having low compatibility with the adhesive to the adhesive layer include the following.
Patent document 1 discloses a patch preparation containing an adhesive, a hardly water-soluble drug, 3 kinds of organic fluid components for dissolution of the hardly water-soluble drug, and cross-linked polyvinyl pyrrolidone. Here, cross-linked polyvinyl pyrrolidone is added to maintain, in the adhesive layer, an organic fluid component having high polarity and low compatibility with the rubber-based adhesive. It is described that, in Comparative Example 4 in which the adhesive layer does not contain cross-linked polyvinyl pyrrolidone, an organic fluid component having high polarity bloomed from the adhesive layer and the adhesive force was not measured.
Patent document 2 discloses a hydrous adhesive composition containing polybutene, a non-ionic surfactant, and an oil-absorbing inorganic powder. This document describes that bleeding of hydrophobic polybutene from the hydrophilic hydrous adhesive composition was solved by the oil-absorbing powder. However, this document is completely silent on the bleeding of an organic fluid component having high polarity from an adhesive layer using a hydrophobic adhesive such as synthetic rubber and a method of solving the bleeding.
As a patch preparation containing magnesium aluminometasilicate in an adhesive layer, for example, patent document 3 describes a patch obtained by extending a plaster containing an A-B-A type thermoplastic elastomer, an alicyclic saturated hydrocarbon resin, liquid paraffin, an efficacy component, and magnesium aluminometasilicate. However, this document merely refers to a method of suppressing a decrease in the cohesive force of a plaster (adhesive layer).